1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor resin molding by molding underfill resin on a semiconductor chip mounted substrate (flip chip mounted substrate) formed by mounting a semiconductor chip on a substrate through a bump (connecting electrode) and a resin member employed therefor.
2. Description of the Background Art
A semiconductor chip mounted substrate on which a plurality of semiconductor chips are mounted through bumps (connecting electrodes) is employed in general. In the semiconductor chip mounted substrate, underfill resin is injected between each of the plurality of semiconductor chips and the substrate in a subsequent step. Thereafter required portions of the resin-injected substrate are cut, for manufacturing individual semiconductor resin moldings.
In the step of injecting the underfill resin, a mold comprising an upper mold section fixed in position and a lower mold section movable in position is employed. In the step of cutting the resin-injected substrate, a cutter comprising a platform sucking the resin-injected substrate thereby fixing the position thereof and a blade (cutting blade) cutting the positionally fixed resin-injected substrate is employed.
Conventional steps of manufacturing a semiconductor resin molding are now more specifically described.
First, both of the upper and lower mold sections are heated to a prescribed temperature in advance of the step of injecting the underfill resin.
Then, the semiconductor chip mounted substrate is fitted into a cavity (concave portion for setting) of the lower mold section. Thereafter the upper and lower mold sections are closed, thereby collectively fitting the plurality of semiconductor chips into a cavity for resin injection provided on the upper mold section.
The underfill resin is heated and melted in a pot for supplying a resin material provided on the lower mold section.
Thereafter the underfill resin is pressurized with a plunger for resin pressurization. Then, the melted underfill resin is injected into the cavity of the upper mold section through a resin passage. Thus, the underfill resin fills up a clearance between each of the plurality of semiconductor chips and the substrate. After a lapse of a time necessary for hardening the underfill resin, the upper and lower mold sections are opened. Thereafter a semiconductor resin-molded substrate resin-molded in the cavity is taken out from the mold.
In general, the heights of the plurality of semiconductor chips, including the thicknesses of the semiconductor chips and the heights of the bumps, are dispersed. Regardless of the depth of the cavity of the upper mold section, i.e., the distance between the mold surface of the upper mold section and the top surface of the cavity, therefore, this dispersion results in the following problems:
When the depth of the cavity of the upper mold section is set to the maximum value among the heights of the semiconductor chips, for example, a clearance is defined between the upper surface of the semiconductor chip other than that having the maximum height and the top surface of the cavity of the upper mold section. Thus, the melted underfill resin infiltrates into this clearance thereby forming a resin molding flash (casting fin) on the upper surface of the semiconductor chip. Further, the semiconductor chips cannot be pressed against the substrate with the top surface of the cavity of the upper mold section. Consequently, the pressure of the melted underfill resin injected into the cavity may exceed mounting force (adhesion) between the semiconductor chips and the substrate. In this case, the semiconductor chips are separated from the substrate due to the fluid pressure of the melted resin. In other words, the semiconductor chip mounted substrate is broken.
When the depth of the cavity of the upper mold section is set to the minimum value among the heights of the semiconductor chips, the upper surface of the semiconductor chip other than that having the minimum depth is strongly pressed against the top surface of the cavity of the upper mold section. Thus, the semiconductor chip mounted substrate is damaged.
When the depth of the cavity of the upper mold section is set to the mean (average) value of the heights of the semiconductor chips, resin molding flashes are readily formed on the upper surfaces of the semiconductor chips and the semiconductor chip mounted substrate is readily damaged.